Anne-Michelle Ruha, M.D., FACMT Department of Medical Toxicology

Banner Good Samaritan Medical Center Phoenix, Arizona

Greatplainslaboratory.com

3 of top 4 sites advise challenge test

  Advocates state: ◦ Current and past exposures result in increased body stores ◦ Challenge reveals ‘body burden’

  Advocates advise: ◦ Comprehensive search for potential sources of Hg exposure  geography, amalgams, fish, high fructose corn syrup, second hand smoke in childhood, exposures of mother prior to conception

Alt Med Review 2009;14(2):103-108.

 What are normal reference ranges for metals in urine after a dose of chelator?

 Diagnostic value? ◦ Can toxicity be ruled in or out based on this test?

  Is it safe?  Does the evidence support use of a challenge test?

 1960s

◦ Fielding proposed a test for measuring ‘chelatable’ iron

◦ A single dose of IV deferoxamine followed by 6 hour urine test

J Clin Path 1965;18:88-9

◦ Rabbit model (Keberle 1964)

 Fe loaded rabbits – 16x increase UFe with red-brown urine

 *Normal rabbits – 5x increase UFe

  IM deferoxamine (about 50 mg/kg)

  If ‘vin rose urine’ within 4-6 hours this would indicate excretion of ferrioxamine

  Imply a toxic level prompting treatment, until urine no longer red

Pediatric Em Med

 No change in urine color in 70% of patients with serum Fe concentrations exceeding expected TIBC

 Recommended that the deferoxamine challenge test be abandoned

Proudfoot AT. Tox Let 1995;82/83:770-783.

  Lead mobilization test: ◦ 24 h urine ◦ 3 doses IM CaNa2EDTA  Every 8 h ◦ 24 h urine

  Study groups: ◦ Control ◦ Suspected Pb

poisoning ◦ Confirmed Pb

poisoning

Pediatrics. 1962;29:384-388.

*All children had increase UPb after challenge Lead poisoned higher UPb than controls

 1980s ◦ Used routinely in children with elevated BPb levels (25-55 ug/dL) to detect ‘mobilizable’ lead

◦ CDC recommended use of lead mobilization test to determine which children would respond to chelation

 Concerns regarding safety ◦ Concern for redistribution of lead ◦ Depletes other metals ◦ Renal toxicity

 Difficult to perform in children

 Data showing lead initially mobilized mainly from bone

Chisolm JJ. AJDC 1987;141:1256-1257

  Used as an adjunctive test in the diagnosis of Wilson Disease ◦ One recommendation is use in symptomatic children if WD is suspected but basal urinary copper excretion is normal

  D-penicillamine 500 mg administered at the onset and 12 hours into a 24 hour urine collection

  Purpose: to re-evaluate conventional diagnostic criteria for WD in children with mild liver disease

  Subjects ◦ 40 with diagnosis of WD ◦ 58 controls – other liver disease and siblings of WD

Hepatology. 2010;52:1948-1956.

Concluded the PCT is of little value for diagnosis in these patients.

 Not recommended: ◦ CaNa2EDTA for lead ◦ Deferoxamine for iron

 Unclear role in dx of Wilson Disease ◦ Penicillamine for copper

  DMSA approved in the US in 1990 for treatment of Pb intoxication

  DMPS ◦ Not approved in US ◦ Used in Russia since 1950s ◦ Approved in Europe in 1970s

◦ Studied as early as the 1950s in Soviet Union and China for treatment of Pb and Hg toxicity

 19 healthy college and grad students  No seafood x 30 days  Amalgam score determined by a dentist (10 with amalgams)

FASEB J. 1992;6:2472-2476.

11 hr pre-DMPS urine collection Oral DMPS 300 mg 9 hr post-DMPS urine collection

•  Amalgam group had higher baseline UHg •  Both groups had rise in UHg (19 fold vs 25 fold) •  Individual cases UHg increased 12- 70 fold

*healthy subjects had up to 70 fold increase in UHg after DMPS

Adverse effects in healthy subjects

2/19 nausea, one vomited

1 rash a week out

FASEB J. 1992;6:2472-2476.

 To assess change in UHg in healthy people given a DMSA challenge test

 UHg correlates with amalgam surfaces

Ann Clin Biochem 2004;41:33-236.

Fasting urine sample Oral DMSA 30 mg/kg 2 h urine sample discarded 3 h urine sample collected

Mean factor increase = 7 Range = 1 to 27 *healthy subjects had up to 27

fold increase in UHg after DMSA

  Intention to include 20 subjects ◦  study closed after 14 completed

 15th developed vomiting, tight chest, urticarial rash 6 minutes after ingestion of DMSA

 3 other subjects with nausea and all reported foul smelling urine x 24 h

Ann Clin Biochem 2004;41:33-236.

 DMSA challenge in healthy individuals with varying amounts of fish intake

 22 volunteers, 30mg/kg oral DMSA

Arch Pathol Lab Med. 2008;132:4-9.

4 9.5 10.8 x

UHg rises in everyone after DMSA challenge

Rise is greater with increased fish intake

 All have urinary Hg excretion even without use of a chelator

 Urinary Hg excretion rises in everyone after a chelation challenge

 10 dental technicians

 5 dentists  13 non-dental personnel

J Pharm and Exp Therapeut 1995;272:264-274

Controls 35 fold increase Dentists 49 fold increase Dental techs 88 fold increase

Pre-DMPS All groups excrete Hg at baseline. Exposed groups more so than controls.

Post-DMPS All groups have rise in UHg.

Overlapping ranges

*one subject nausea/diarrhea

14-132 45-76 11-335

*Healthy controls with up to 132x rise in UHg after DMPS

 DMPS challenge to:

 11 factory workers ◦ (made HgCl - containing skin lotion)

 8 lotion users  9 controls

JPET 1996;277:938-944

Makers: increased 45 x Users: increased 87 x Controls: increased 38 x

All groups excrete Hg before DMPS Large baseline differences in UHg

  Test whether DMPS challenge could provide index of the Hg body burden due to long-term exposure

  All healthy subjects with little fish intake

  41 men in 4 groups ◦  10 industrial workers (m exposure =11yrs) ◦  8 dentists (m = 33 yrs) ◦  18 occupationally unexposed ◦  5 occ unexposed and amalgam free

Int Arch Occup Environ Health. 1991;63:187-192.

•  All groups excrete Hg at baseline •  Exposed populations have greater baseline UHg •  UHg excretion rises in all groups after DMPS

Average increase: 10 x 5.9 x 5.3 x 3.8 x

  Pre-DMPS UHg excretion was associated with post-DMPS UHg excretion in all groups

 Authors concluded the challenge test did not reflect long term exposure (body burden)

 Does DMSA challenge reveal increased body burden of Hg with remote occupational exposure to Hg?

 Chloralkali plant workers with long-term, high-level exposure; controls

  Exposure profiles - based on specific jobs, historical air sampling data ◦ Average, cumulative, and peak exp

Environ Health Perspect 2001;109:167-171

Authors conclude DMSA challenge not useful in quantifying past mercury exposure

15 subjects with highest exposure rank

Range for this highest exposure group 3x -114x increase

 Recognize ◦ UHg concentrations reported differently (mcg, mcg/L, mcg/gCr) ◦ Urine collections vary (spot – 24 h) ◦ Dose of chelating agent varies ◦ Results may not be comparable with different chelators

  Baseline urine Hg concentrations are higher in exposed populations than in unexposed populations

  DMPS and DMSA challenges produce a rise in urine Hg excretion in all groups

  There is great overlap in factor increase between and within exposure groups

Study Chelator # subjects Hg (mean; upper range)

Aposhian DMPS 10 (no amal) 5±1mcg/9h

10 (amal) 17±3 mcg/9h

Archbold DMSA 14 14 ± 14 mcg/L

Ruha DMSA 22 3/10/13; 33 mcg/gCr

Gonzalez-Ramirez DMPS 13 27 ±3 mcg/6h

OR 37±15 mcg/L

Maiorino DMPS 9 18±7; 54 mcg/6h OR 22±10; 73 mcg/L

Molin DMPS 5 (no amal) 3.2 mcg/24h

18 (no amal) 14; 56 mcg/24h

Frumkin DMSA 101 8±6; 28 mcg/24h

Reference range (post-challenge) in healthy populations?

µg/gCr

 No randomized, controlled studies comparing use of a challenge test in subjects with metal poisoning to those without metal poisoning

◦ Metal toxicity would have to be diagnosed based on known exposure and clinical findings consistent with and specific for toxicity

 Reports that describe patients with vague symptoms that are non-diagnostic for Hg toxicity who are given a challenge test and diagnosed on the basis of ◦ An increase in metal excretion ◦ Report of symptom improvement

 DMPS challenge test (2 mg/kg IV) to: ◦ 19 without amalgams and healthy ◦ 21 with amalgams and healthy ◦ 20 with amalgams and self-diagnosed Hg poisoning ◦ 20 who had amalgams removed because of self-diagnosed Hg poisoning

J Dent Res 2000;79(3):868-874.

 The amalgam groups excreted 3x as much Hg as the amalgam free groups

 No difference between amalgam groups with and without symptoms  (the symptomatic group did not have a larger ‘body burden’ detected with challenge test)

  Grandjean P, et al. Placebo response in environmental disease: chelation therapy of patients with symptoms attributed to amalgam fillings.

  Double blind RCT

  Patients who attributed symptoms to amalgams (no alternative dx)

  DMSA 30 mg/kg divided TID x 5 days

  Both groups reported improvement

J Occ and Env Med 1997;39(8):707-714.

 Adverse reactions widely reported   Potential for mineral deficiencies  Other unpleasant side-effects ◦ Foul-smell ◦ Nausea

 Cost

 No established reference ranges  No evidence for diagnostic value  Not universally safe

 NO

1.  Charlton N and Wallace KL. Post-chelator challenge urinary metal testing. AMCT position statement. http://www.acmt.net/cgi/page.cgi?aid=2999&_id=52&zine=show (accessed19 Jan 2012)

2.  Risher JF, Amler SN. Mercury exposure: evaluation and intervention The inappropriate use of chelating agents in the diagnosis and treatment of putative mercury poisoning. NeuroToxicology 2005;26:691-699.

3.  Keberle H. The biochemistry of desferrioxamine and its relation to iron metabolism. Ann NY Acad Sci 119:758-768, 1964

4.  Fielding J. Differential ferrioxamine test for measuring chelatable body iron. J Clin Path 1965;18:88-9

5.  Proudfoot AT. Antidotes: benefits and risks. Tox Let 1995;82/83:770-783. 6.  Whitaker JA, Austin W, Nelson JD. Edathamil calcium disodium (versenate) diagnostic

test for lead poisoning. Pediatrics. 1962;29:384-388. 7.  Markowitz ME and Rose JF. Need for the lead mobilization test in children with lead

poisoning. J Pediatr 1991;19:305-310. 8.  Chisolm JJ. Mobilization of lead by calcium disodium edetate. AJDC.

1987;141:1256-1257 9.  Nicastro E, Ranucci G, et al. Re-evaluation of the diagnostic criteria for Wilson Disease

in children with mild liver disease. Hepatology. 2010;52:1948-1956. 10.  Vieira et al. Urinary copper excretion before and after oral intake of D-penicillamine in

parents of patients with Wilson’s disease. Digestive and Liver Disease 2011 (E pub) 11.  Lee Byung-Kook, et al. Provactive chelation with DMSA and EDTA: evidence for

differential access to lead storage sites. Occup and Environ Med 1995;52:13-19

12. Archbold GP, McGuckin RM, and Campbell NA. Dimercaptosuccinic acid loading test for assessing mercury burden in healthy individuals. Ann Clin Biochem 2004;41:33-236.

13. Ruha AM, Curry SC, Gerkin RD, et al. Urine mercury excretion following DMSA challenge in fish eaters. Arch Pathol Lab Med. 2008;132:4-9.

14. Aposhian HV, Bruce DC, Wilfred A, et al. Urinary mercury after administration of 2,3-dimercaptopropane-1-sulfonic acid: correlation with dental amalgam score. FASEB J. 1992;6:2472-2476.

15. Gonzalez-Ramirez D, Maiorino RM, et al. Sodium 2,3-dimercaptopropane-1-sulfonate challenge test for mercury in humans: II. Urinary mercury, porphyrins, and neurobehavioral changes of dental workers in Monterrey, Mexico. The Journal of Pharmacology and Experimental Therapeutics. 1995;272:264-274

16. Maiorino RM, et al. Sodium 2,3-dimercaptopropane-1-sulfonate challenge test for mercury in humans. III. Urinary mercury after exposure to mercurous chloride. JPET 1996;277:938-944

17. Molin M, Schiitz A, et al. Mobilized mercury in subjects with varying exposure to elemental mercury vapour. Int Arch Occup Environ Health. 1991;63:187-192.

18. Frumkin H, et al…Diagnostic Chelation Challenge with DMSA: A biomarker of long-term mercury exposure? Environ Health Perspect 2001;109:167-171

19. Vamnes JS, Eide R, Isrenn R, et al. Diagnostic value of a chelating agent in patients with symptoms allegedly caused by amalgam fillings. J Dent Res 2000;79(3):868-874.

20. Grandjean P, Guldager B, Larsen IB, et al. Placebo response in environmental disease: chelaiton therapy of ptients with symptoms attibuted to amalgam fillings. 1997;39(8):707-714.

21. Crinnion WJ. The benefit of pre- and post-challenge urine heavy metal testing: part 2. Alt Med Review 2009;14(2):103-108.